Probiotic effects of orally administered Lactobacillus salivarius WB21‐containing tablets on periodontopathic bacteria: a double‐blinded, placebo‐controlled, randomized clinical trial

Aim: This study was designed to evaluate whether the oral administration of lactobacilli could change the bacterial population in supra/subgingival plaque. Material and Methods: Sixty-six healthy volunteers without severe periodontitis were randomized into two groups to receive lactobacilli or placebo for 8 weeks (8W): the test group (n = 34) received 2.01 x 10 9 CFU/day of Lactobacillus salivarius WB21 and xylitol in tablets; the control group (n = 32) received placebo with xylitol. Supra/subgingival plaque samples were collected at the baseline and after 4 weeks (4W) and 8W. The bacterial amounts in plaque samples were analysed by quantitative real-time polymerase chain reaction. Results: The numerical sum of five selected periodontopathic bacteria in the test group was decreased significantly in subgingival plaque at 4W [odds ratio (OR) = 3.13, 95% confidence intervals (CI) = 1.28-7.65, p = 0.012]. Multivariate analysis showed that significantly higher odds were obtained for the reduction of Tannerella forsythia in subgingival plaque of the test group at both 4W (OR = 6.69, 95% CI= 2.51-17.9, p<0.001) and 8W (OR = 3.67, 95% CI = 1.45-9.26,p = 0.006). Conclusion: Oral administration of probiotic lactobacilli reduced the numerical sum of five selected periodontopathic bacteria and could contribute to the beneficial effects on periodontal conditions.